The effect of wall conditioning on a plasma was studied in the Gas Dynamic Trap (GDT) facility by means of titanium coating of the containment wall. After depositing titanium on the inner surface of the vacuum chamber the charge-exchange losses of the fast ions turned out to be much less than in former, non-conditioned discharges. The temporal and spatial variation of the neutral gas density was measured during typical shots and calculated by means of a Monte Carlo transport code. The comparison of the results numerical simulation with the experimental data are presented.